The Herschel SPIRE Fourier Transform Spectrometer Spectral Feature Finder III. Line Identification and Off-Axis Spectra

TL;DR

This paper extends the Herschel SPIRE FTS spectral feature finder to include off-axis spectra and automates the identification of atomic and molecular lines, significantly enhancing spectral feature cataloging.

Contribution

It introduces an extension to include off-axis detector data and an automated line identification routine, improving spectral feature detection and catalog completeness.

Findings

Identified 178,942 atomic/molecular lines, covering 83% of the catalogue.

Added 33,840 missing spectral lines to the catalogue.

Enhanced spectral feature detection for SPIRE FTS observations.

Abstract

The ESA Herschel Spectral and Photometric Imaging Receiver (SPIRE) Fourier Transform Spectrometer (FTS) Spectral Feature Finder (FF) project is an automated spectral feature fitting routine developed within the SPIRE instrument team to extract all prominent spectral features from all publicly available SPIRE FTS observations. We present the extension of the FF to include the off-axis detectors of the FTS in sparsely sampled single-pointing observations, the results of which have been ingested into the catalogue. We also present the results from an automated routine for identifications of the atomic/molecular transitions that correspond to the spectral features extracted by the FF. We use a template of 307 atomic fine structure and molecular lines that are commonly found in SPIRE FTS spectra for the cross-match. The routine makes use of information provided by the line identification to search for low signal-to-noise ratio features that have been excluded or missed by the iterative FF. In total, the atomic/molecular transitions of 178,942 lines are identified (corresponding to 83% of the entire FF catalogue), and an additional 33,840 spectral lines associated with missing features from SPIRE FTS observations are added to the FF catalogue.